Fix React hooks ordering in post feed item

By specifier.

src/components/post-feed/post-feed-item.js

@@ -31,12 +31,14 @@ function PostFeedItem ({
   showLikeButton = true,
   embedded = false
 }) {
-  if (!post) return null
+  // React hooks must be called unconditionally before any early return, so
-
+  // declare the like state first and guard the post access after.
   const [liked, setLiked] = useState(false)
-  const [likeCount, setLikeCount] = useState(post.likeCount || 0)
+  const [likeCount, setLikeCount] = useState(post?.likeCount || 0)
   const [showLikeModal, setShowLikeModal] = useState(false)
 
+  if (!post) return null
+
   const displayName = getDisplayName(post.addr, profiles)
 
   const hasCustomName = Boolean(